Many different types of yarns made of natural fibers are known in the art. One well known example is paper yarn, which is traditionally manufactured from paper sheets. The first and only industrial method was developed in the late 19th century in Germany. It has been refined over time but the basic principle has remained the same and it is still in use today. Typically, paper manufactured from chemical, mechanical or chemi-mechanical pulp is slit to strips (width typically from 5 to 40 mm), which are twisted to thread. Said thread may be subjected to dyeing and finishing. The product (paper yarn) has limited applications because of deficiencies in its properties, such as limited strength, unsuitable thickness, layered or folded structure, and further, the manufacturing method is inefficient.
Cotton is very widely used as raw material in the manufacture of yarns and ropes. However, the cultivation of cotton requires significant water resources and it is widely carried out in regions where there is shortage of water and food. When available water is used for the irrigation of cotton fields, the situation with regard to food supply becomes worse. Thus the use of cotton does not support sustainable development, and there is a need for alternative sources of fiber, suitable for replacing cotton at least partly.
Cotton farming covers 5% of the world's farming area but it uses 11% of all agrochemicals. Intensive farming of cotton has caused pollution to the waters, wear of the soil and it has changed the animal population. In the future highly pollutant cotton can be replaced by cellulose based materials. There are already alternatives to cotton. Rayon is a material produced from cellulose fibers but it still requires heavy chemical treatments.
Methods for producing fibre yarn and other products from cellulosic materials are described in documents JP 4004501 B, JP 10018123, JP 2004339650, JP 4839973, EP 1493859, CN 102912622, CN 101724931, WO 2009028919 and DE 19544097. The methods described usually include chemical treatment of cellulose before or during manufacture of the product.